Synthesis of C1- and C 3ν-symmetric porphyrin trimers based on triphenylmethane cores

Article abstract of DOI:10.1007/s00706-007-0629-y

This work describes the synthesis of a new class of tripodaphyrin derivatives with a triphenylmethane core. Both C ₁- and C _3ν-symmetric tetrahedral large molecules with covalently linked rigid elements were obtained.

Full text of DOI:10.1007/s00706-007-0629-y

Monatshefte fu¨r Chemie 138, 791–796 (2007)
DOI 10.1007/s00706-007-0629-y
Printed in The Netherlands
Synthesis of C1- and C3m-Symmetric Porphyrin Trimers Based
on Triphenylmethane Cores
1;ꢀ
Cyril A. Papamicael , Olivier Mongin2, and Albert Gossauer3
¨
1
´ ´
UMR 6014 IRCOF, CNRS, Universite et INSA de Rouen, Mont-Saint-Aignan Cedex, France
´
2
` `
Synthese et ElectroSynthese Organiques (CNRS, UMR 6510), Universite de Rennes 1, Institut de Chimie,
´
Campus Scientifique de Beaulieu, Rennes Cedex, France
3
¨
Institut fu¨r Organische Chemie der Universitat, Fribourg, Switzerland
Received January 30, 2007; accepted (revised) February 24, 2007; published online May 23, 2007
# Springer-Verlag 2007
Summary. This work describes the synthesis of a new class
lently linked rigid constitutives elements. Our prin-
of tripodaphyrin derivatives with a triphenylmethane core.
Both C1- and C3ꢀ-symmetric tetrahedral large molecules with
covalently linked rigid elements were obtained.
cipal aims of applications of tripodaphyrins are both
studies of these molecules as light-harversting sys-
tems arrays and molecular-based information stor-
age. Indeed, one can envisage that multiple bits of
information could be stored through the positioning
of (ꢁ)-chiral tripodaphyrins by means of scanning
probe microscopy (STM=AFM). In the present work,
we describe the full synthetic details of C1- and C3ꢀ-
symmetric tripodaphyrin derivatives.
Keywords. Porphyrines; Alkynes; Nanostructures; Chirality;
Tripodaphyrin.
Introduction
The design and construction of novel porphyrin ar-
chitectures with well-defined geometries is an area
of increasing current interest [1]. Multi-porphyrins
macrorings have attracted enormous interest because
porphyrins provide rigid frameworks with relatively
easy synthesis approaches [2]. Their biological im-
portance, as it was found that the antenna chloro-
phylls in photosynthetic bacteria are arranged into
macrorings to absorb and transfer solar energy with
great efficiency, makes them one of the attracting re-
search targets. In preceding papers [3, 4] we de-
scribed the synthesis of tripodaphyrins, a new class
of porphyrine derivatives. Tripodaphyrins are pyra-
midal assemblies in which a porphyrin macrocycle,
situated on the top of the molecule, is ‘‘supported’’
by three ‘‘legs’’ consisting of linear arrays of cova-
Results and Discussion
As a starting point for the design of a C3ꢀ-sym-
metric tripodaphyrin derivative, we choose readily
available 4,40,400-methylidynetrisphenol [5] skele-
ton 1. Its reaction with a threefold excess of trifluoro-
methanesulfonyl chloride afforded the expected
compound 2 in 80% yield. Substitution of all three
triflate groups by ethynyl groups was achieved in
95% yield on reaction of 2 with triisopropylsilyl-
acetylene under Pd(0)-catalyzed conditions using cop-
per iodide (Scheme 1). Thereafter, cleavage of both
trialkylsilyl protecting groups gave the core mole-
cule 4 (70%), which was reacted with [5-(4-iodo-
phenyl)-10,15,20-triphenylporphinato(2-)]zinc [4] to
afford the desired C3ꢀ-symmetric porphyrin trimer 6
in 49% yield.
ꢀ
rouen.fr
Corresponding author. E-mail: cyril.papamicael@insa-

¨
C. A. Papamicael et al.
792
Scheme 1
The strategy devised for the synthesis of a (ꢁ)-
arsine as a ligand of the palladium catalyst instead
of triphenylphosphine [7]. The porphyrin trimer 16
with three ‘‘arms’’ of different lengths (C1-symme-
try) was synthesized after cleavage of both trialkyl-
silyl protecting groups in 85% yield and coupling
with tetraphenylporphyrine 15 elongated with an
iodotolane [4] unit (18%) (Scheme 3).
In conclusion, we developed a synthesis to obtain
a new class of tripodaphyrins derivatives designed
for nanofabrication. On one hand, we synthesized a
C3ꢀ-symmetric triphenylmethane in which three por-
phyrin macrocycles are attached to each phenyl ring.
On the other hand, by using successive substitution of
the three iodine atoms of tris(4-iodophenyl)methane,
chiral tripodaphyrin derivative (C1-symmetry) was
based upon the use of pure [6] tris(4-iodophenyl)-
methane (8), which was prepared in 89% yield start-
ing from 7. Then, successive replacement of the
iodine atoms of triphenylmethane 8 by Sonogashira
coupling reactions with ethynyltrimethylsilane and
compound 10 [8] was possible yielding 9 (41%)
and 11 (40%). Thus, a (ꢁ)-chiral triphenylmethane
core was obtained (Scheme 2).
As a precursor of the (ꢁ)-chiral tripodaphyrin
derivative, compound 13 was prepared in 88% yield
by coupling 11 and [5-(4-ethynylphenyl)-10,15,20-
triphenylporphinato(2-)]zinc (12) [4] using triphenyl-

Synthesis of C1- and C3ꢀ-Symmetric Porphyrin Trimers
793
Scheme 2
ture of 149mg 4,40,400-methylidynetrisphenol [5] (0.51 mmol),
0.348 cm3 Et3N (2.5mmol), and 6.2 mg DMAP (0.051mmol) in
4.3 cm3 dry acetone at 0ꢃC. After being stirred for 3 h at 0ꢃC,
the solvent was removed under reduced pressure and the crude
product was purified by CC (CH2Cl2=n-hexane ¼ 1=4) to yield
280 mg (80%) 2. M.p.: 82ꢃC; 1H NMR (200.00 MHz, CDCl3):
ꢂ ¼ 5.64 (s, 1H, CH), 7.15 and 7.25 (AA0XX0, 2ꢄapparent d,
J ¼ 8.9Hz, 12H, H-2, H-3) ppm; 13C NMR (50.30 MHz,
CDCl3): ꢂ ¼ 54.7 (CH), 118.7 (q, J ¼ 321 Hz, CF3), 121.7
(C-2), 131.0 (C-3), 142.5 (C-4), 148.5 (C-1) ppm; FAB-MS:
m=z (%) ¼ 687 ([M ꢂ H]þ, 19), 555 (25), 463 (100).
a trimer with three ‘‘arms’’ of different length was
also obtained.
Experimental
All air- or water-sensitive reactions were carried out under Ar.
Solvents were generally dried and distilled prior to use.
Reactions were monitored by thin-layer chromatography on
E. Merck silica gel 60F254 (0.2mm) precoated aluminum foils.
Column chromatography (CC): E. Merck silica gel 60 (230–
400 mesh). Melting points (m.p.) were determined with a hot
stage apparatus (Thermovar, C. Reichert AG, Vienna) equipped
with a digital thermometer. UV=VIS spectra were recorded
on a Hewlett-Packard-8452A diode-array spectrophotometer;
ꢁmax in nm (log" in molꢂ1 dm3 cmꢂ1). NMR: Varian Gemini
200 (1H: 200.00 MHz; 13C: 50.30 MHz), Bruker-AM 360 (1H:
360.14 MHz), or Bruker Avance DRX 500 (1H: 500.13MHz;
13C: 125.76 MHz); 1H and 13C chemical shifts (ꢂ) are given in
ppm relative to TMS as internal standard, J values in Hz. Mass
spectra: Vacuum Generators Micromass 7070E instrument
equipped with a data system DS 11–250, FAB (fast atom
bombardment): in 2-nitrobenzyl alcohol with Ar at 8 kV. Ele-
mental analysis (C, H, N) were conducted by Ciba Specialities
Mikrolabor, Marly, Switzerland, their results were found to
be in good agreement (ꢁ0.2%) with the calculated values.
Tetrakis(triphenylphosphine)palladium, tris(dibenzylideneace-
tone)dipalladium (Pd2dba3), triphenylarsine and tetrabutyl-
ammonium fluoride (TBAF) were purchased from Aldrich;
dimethylformamide (DMF), tetrahydrofuran (THF), trimethyl-
silylacetylene (TMSA), triisopropylsilylacetylene, and other
reagents from Fluka.
[Methylidynetris(4,1-phenylene-2,1-ethynediyl)]
tris(triisopropylsilane) (3, C52H76Si3)
Air was removed from a soln. of 82.5mg 2 (0.12 mmol) in
7 cm3 DMF=Et3N (5:1) by blowing Ar for 20 min. Then
41.7mg Pd(PPh3)4 (0.036mmol), 13.8mg CuI (0.072 mmol),
and 0.134mm3 ethynyltriisopropylsilane (0.6mmol) were
added, and deaeration was continued for 10 min. Thereafter,
the mixture was heated at 45ꢃC for 18h. The solvent was
removed under reduced pressure and the crude product was
purified by CC (n-hexane) to yield 89.6 mg (95%) 3. M.p.:
167ꢃC; 1H NMR (200.00 MHz, CDCl3): ꢂ ¼ 1.12 (m, 63H, Sii-
Pr3), 5.49 (s, 1H, CH), 6.99 and 7.39 (AA0XX0, 2ꢄapparent
d, J ¼ 8.2Hz, 12H, H-2, H-3) ppm; 13C NMR (50.30 MHz,
CDCl3): ꢂ ¼ 11.3 (SiCH), 18.7 (CH(CH3)2), 56.3 (CH), 90.6
(CꢅC-Sii-Pr3), 106.8 (CꢅC-Sii-Pr3), 121.9 (C-1), 129.2
(C-3), 132.1 (C-2), 143.3 (C-4) ppm; FAB-MS: m=z (%) ¼
786 (M, 57), 742 (100).
Tris(4-ethynylphenyl)methane (4, C25H16)
To a solution of 23.7mg 3 (30.2 ꢃmol) in 8 cm3 THF, 18mm3
TBAF (1M in THF, 18 ꢃmol) were added at 0ꢃC, and the
mixture was stirred at 0ꢃC for 10 min. A few grains of
CaCl2 were added and the solvent was evaporated. The crude
product was purified by CC (gradient from n-hexane to
CHCl3=n-hexane¼ 9=1) to yield 6.7 mg (70%) of 4. 1H NMR
Trifluoromethanesulfonic acid methylidynetri-4,1-
phenylene ester (2) [10]
Trifluoromethanesulfonyl chloride (0.178 cm3, 1.68mmol)
was slowly added under an Ar atmosphere to a stirring mix-

¨
C. A. Papamicael et al.
794
Scheme 3
(360.14 MHz, CDCl3): ꢂ ¼ 3.05 (s, 3H, CꢅCH), 5.52 (s, 1H,
CH), 7.02 and 7.42 (AA0XX0, 2ꢄapparent d, J ¼ 8.1 Hz, 12H,
H-2, H-3) ppm; 13C NMR (50.30 MHz, CDCl3): ꢂ ¼ 56.3
(CH), 77.3 (CꢅC–H), 83.3 (CꢅC–H), 120.5 (C-4), 129.3
(C-2), 132.3 (C-3), 143.6 (C-1) ppm; FAB-MS: m=z (%) ¼
317 (Mþ, 31), 215 (100).
at 35ꢃC for 6 h. At that time, the same amount of Pd2(dba)3
and AsPh3 was again added and the stirring continued for 3 h.
The solvent was removed under reduced pressure and the crude
product was purified by two successive CC (CHCl3=n-hexane:
gradient from 3=2 to 3=1) to yield 8.1mg (49%) 6. UV=VIS
(CH2Cl2): ꢁmax (log ") ¼ 298 (4.94), 420 (6.10), 548 (4.69),
578 (3.96), 586 (4.14), 594 (3.69) nm (molꢂ1 dm3 cmꢂ1);
1H NMR (360.14 MHz, CDCl3): ꢂ ¼ 5.72 (s, 1H, CH),
7.28 and 7.70 (AA0XX0, 2ꢄapparent d, J ¼ 8.4 Hz, 12H, H-
phenylene), 7.72–7.81 (m, 27H, m- and p-H-phenyl)), 7.96
(apparent d, J ¼ 8.0 Hz, 6H, H-phenylene on porphyrin),
8.19–8.26 (m, 24H, o-H-phenyl and H-phenylene on por-
phyrin), 8.95 (s, 12H, ꢄ-H on porphyrin ouside), 8.98
(s, 12H, ꢄ-H on porphyrin inside) ppm; ESþ-MS (in CHCl3=
C3ꢀ-Symmetric Triporphyrin (6, C157H94N12Zn3)
Air was removed from a soln. of 2.2 mg 4 (7 ꢃmol) and
22.7 mg [5-(4-iodophenyl)-10,15,20-triphenylporphinato
(2-)]zinc (5) [4] (28.2 ꢃmol) in 4.8 cm3 DMF=Et3N (5=1) by
blowing Ar for 20min. Then 0.79 mg Pd2(dba)3 (0.86 ꢃmol)
and 2.11 mg AsPh3 (6.89 ꢃmol) were added, and deaeration
was continued for 10min. Thereafter, the mixture was heated

Synthesis of C1- and C3ꢀ-Symmetric Porphyrin Trimers
795
HCOOH): m=z ¼ 1078.0 ([M-3Zn þ 8H]2þ), 719.2 ([M-
3Zn þ 9H]3þ) (calc. avg. mass for C157H94N12Zn3: 2344.69).
C-400), 123.2, 123.5 (C-40, C-1000), 129.2, 129.4 (C-3, C-20),
131.4 (C-2 iodophenyl), 131.5, 131.6, 131.8 (C-30, C200,
C-300, C-2000), 132.0, 132.1 (C-2, C-3000), 137.6 (C-3 iodophe-
nyl), 142.6 (C-1 iodophenyl), 143.2, 143.3 (C-4, C-10) ppm;
FAB-MS: m=z (%) ¼ 847 (Mþ, 100), 803 (53).
Tris(4-iodophenyl)methane (8) [6]
A soln. of 162.4mg tris(4-iodophenyl)methanol (0.25 mmol)
was refluxed in 98% HCOOH for 22 h. Thereafter, the soln.
was diluted with CH2Cl2 and water. The mixture was neu-
tralized with solid NaHCO3, extracted three times with
CH2Cl2, dried (Na2SO4), and evaporated. The crude prod-
uct was purified by CC (CH2Cl2=n-hexane ¼ 1=19) to yield
140.4 mg (89%) 8. 1H NMR (200.00 MHz, CDCl3): ꢂ ¼ 5.35
(s, 1H, CH), 6.80 and 7.61 (AA0XX0, 2ꢄapparent d,
J ¼ 8.2 Hz, 12H, H-phenylene) ppm; 13C NMR (50.30 MHz,
CDCl3): ꢂ ¼ 55.4 (CH), 92.3 (C-4), 131.2 (C-2), 137.6 (C-3),
142.3 (C-1) ppm.
[10,15,20-Triphenyl-5-[4-[[4-[[4-[[4-[[4-[(triisopropyl-
silyl)ethynyl]phenyl]ethynyl]phenyl]ethynyl]-phenyl]-[4-
[(trimethylsilyl)ethynyl]phenyl]methyl]phenyl]ethynyl]-
phenyl]porphinato(2-)]zinc (13, C97H78N4Si2Zn)
Air was removed from a soln. of 6.0 mg 11 (7.1 ꢃmol)
and 20 mg [5-(4-ethynylphenyl)-10,15,20-triphenylporphi-
nato(2-)]zinc 12 [4] (28.5 ꢃmol) in 2.4 cm3 of DMF=Et3N
(5=1) by blowing Ar for 20 min. Then 0.41 mg Pd2(dba)3
(0.45 ꢃmol) and 1.09 mg AsPh3 (3.56 ꢃmol) were added, and
deaeration was continued for 10 min. Thereafter, the mix-
ture was heated at 40ꢃC for 4 h. At that time, the same amount
of Pd2(dba)3 and AsPh3 was again added and the stirring
continued for 3 h. The solvent was removed under reduced
pressure and the crude product was purified by CC (CHCl3=
n-hexane: gradient from 2=3 to 11=9) to yield 8.9 mg (88%)
13. UV=VIS (CH2Cl2): ꢁmax (log ") ¼ 336 (4.86), 360 (4.72),
422 (5.68), 548 (4.34), 588 (3.84) nm (molꢂ1 dm3 cmꢂ1);
1H NMR (500.13MHz, CDCl3): ꢂ ¼ 0.26 (s, 9H, SiMe3),
1.13 (s, 21H, Sii-Pr3), 5.60 (s, 1H, CH), 7.09 and 7.45
(AA0XX0, 2ꢄapparent d, J ¼ 8.3 Hz, 4H, H-trimethylsily-
lethynylphenyl), 7.12 and 7.50 (AA0XX0, 2ꢄapparent d,
J ¼ 8.3Hz, 4H, H-phenylene-CH in big ‘‘leg’’), 7.15 and
7.61 (AA0XX0, 2ꢄ apparent d, J ¼ 8.2 Hz, 4H, H-phenylene-
CH in porphyrin ‘‘leg’’), 7.46 (m, 4H, H-triisopropylsilylethy-
nylphenyl), 7.51 (m, 4H, H-central phenylene), 7.73–7.80 (m,
9H, m- and p-H-phenyl), 7.92 (apparent d, J ¼ 8.2 Hz, 2H,
H-phenylene on porphyrin), 8.21–8.23 (m, 8H, o-H-phenyl
and H-phenylene on porphyrin), 8.96 (m, 8H, ꢄ-H on por-
phyrin) ppm; FAB-MS: m=z (%) ¼ 1420.9 (calc. avg. mass
for C97H78N4Si2Zn: 1421.26).
[[4-[[Bis-(4-iodophenyl)]methyl]phenyl]ethynyl]-
trimethylsilane (9, C24H22I2Si)
Air was removed from a soln. of 130.3 mg tris(4-iodophe-
nyl)methane (8) [6] (0.21 mmol) in 7.4 cm3 pyridine=Et3N
(1=1) by blowing Ar for 20 min. Then, 8.3 mg Pd(PPh3)4
(7.2 ꢃmol), 4.4 mg CuI (23 ꢃmol), and 26 mm3 TMSA
(0.187 mmol) were added, and the mixture was stirred at 35ꢃC
for 2 h. The solvent was removed under reduced pressure and
the residue was purified by CC (CH2Cl2=n-hexane¼ 1=19)
1
to yield 45.4mg (41%) 9. H NMR (360.14 MHz, CDCl3):
ꢂ ¼ 0.24 (s, 9H, SiMe3), 5.39 (s, 1H, CH), 6.79 and 7.60
(AA0XX0, 2ꢄapparent d, J ¼ 8.6 Hz, 8H, H-iodophenyl),
6.97 and 7.38 (AA0XX0, 2ꢄapparent d, J ¼ 8.2 Hz, 4H, H-
phenylene) ppm; 13C NMR (50.30 MHz, CDCl3): ꢂ ¼ ꢂ0.05
(SiMe3), 55.6 (central CH), 92.2 (C-40), 94.5 (CꢅC-SiMe3),
104.6 (CꢅC-SiMe3), 121.6 (C-1), 129.1 (C-3), 131.3 (C-20),
132.1 (C-2), 137.6 (C-30), 142.5 (C10), 143.0 (C-4) ppm; FAB-
MS: m=z (%) ¼ 592 (Mþ, 24), 591 ([M ꢂ H]þ, 46), 577
([M ꢂ CH3]þ, 69), 419 ([M ꢂ H ꢂ I ꢂ 3CH3]þ, 95), 389 (100).
[[4-[[(4-Iodophenyl)-[4-[[4-[[4-[(triisopropylsilyl)ethynyl]-
phenyl]ethynyl]phenyl]ethynyl]phenyl]]methyl]phenyl]-
ethynyl]trimethylsilane (11, C51H51ISi2)
[5-[4-[[4-[(4-Ethynylphenyl)-[4-[[4-[(4-ethynylphenyl)-
ethynyl]phenyl]ethynyl]phenyl]methyl]phenyl]ethynyl]-
phenyl]-10,15,20-triphenylporphinato(2-)]zinc
Air was removed from a soln. of 32 mg 9 (54 ꢃmol) and
18.8 mg [[4-[(4-ethynylphenyl)ethynyl]phenyl]ethynyl]triis-
propylsilane (10) [8] (49 ꢃmol) in 3 cm3 pyridine=Et3N (1=1)
by blowing Ar for 20 min. Then, 3 mg Pd(PPh3)4 (2.6ꢃmol)
and 2.2 mg CuI (12 ꢃmol) were added, and the mixture was
stirred at 35ꢃC for 2 h. The solvent was removed under re-
duced pressure and the residue was purified by CC (gradient
from n-hexane to CH2Cl2=n-hexane ¼ 2=23) to yield 16.7 mg
(14, C85H50N4Zn)
Compound 14 was obtained in 85% yield (6.4mg), as de-
scribed for 4, from 8.9 mg 13 (6.3ꢃmol) for 8 min, after puri-
fication by CC (CHCl3=n-hexane¼ 11=9). UV=VIS (CH2Cl2):
ꢁmax (log ") ¼ 334 (4.79), 354 (4.62), 420 (5.62), 548 (4.19),
590 (3.47) nm (molꢂ1 dm3 cmꢂ1); 1H NMR (360.14 MHz,
CDCl3): ꢂ ¼ 3.09 (s, 1H, CꢅCH), 3.18 (s, 1H, CꢅCH in big
‘‘leg’’), 5.61 (s, 1H, CH), 7.12 and 7.48 (AA0XX0, 2ꢄ
apparent d, J ¼ 8.3 Hz, 4H, H-phenylene-CH), 7.13 and 7.50
(AA0XX0, 2ꢄapparent d, J ¼ 8.3Hz, 4H, H-phenylene-CH),
7.16 and 7.62 (AA0XX0, 2ꢄapparent d, J ¼ 8.3Hz, 4H, H-
phenylene-CH in porphyrin ‘‘leg’’), 7.48 (m, 4H, H-phenylene
in big ‘‘leg’’), 7.51 (m, 4H, H-central phenylene in big ‘‘leg’’),
7.72–7.80 (m, 9H, m- and p-H-phenyl), 7.92 (apparent d,
J ¼ 8.3Hz, 2H, H-phenylene on porphyrin), 8.20–8.23 (m,
8H, o-H-phenyl and H-phenylene on porphyrin), 8.96 (m,
8H, ꢄ-H on porphyrin) ppm; FAB-MS: m=z (%) ¼ 1193.1
(calc. avg. mass for C85H50N4Zn: 1192.74).
1
(40%) 11. M.p.: 73ꢃC; H NMR (360.14 MHz, CDCl3): ꢂ ¼
0.24 (s, 9H, SiMe3), 1.13 (m, 21H, Sii-Pr3), 5.47 (s, 1H, CH),
6.82 and 7.61 (AA0XX0, 2ꢄapparent d, J ¼ 8.5 Hz, 4H, H-
iodophenyl), 7.00 and 7.39 (AA0XX0, 2ꢄapparent d, J ¼
8.3 Hz, 4H, H-2, H-3), 7.03 and 7.44 (AA0XX0, 2ꢄapparent
d, J ¼ 8.0 Hz, 4H, H-20, H-30), 7.45 (m, 4H, H-2000, H-3000), 7.49
(m, 4H, H-200, H-300) ppm; 13C NMR (50.30MHz, CDCl3):
ꢂ ¼ ꢂ0.05 (SiMe3), 11.3 (SiCH), 18.7 (CH(CH3)2), 56.0 (cen-
tral CH), 89.2, 90.9, 91.0, 91.1 (CꢅC), 92.2 (C-4 iodophenyl),
93.0 (CꢅC-Sii-Pr3), 94.4 (CꢅC–SiMe3), 104.7 (CꢅC–SiMe3),
106.6 (CꢅC–Sii-Pr3), 121.4, 121.6 (C-1, C-4000), 122.8 (C-100,

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C. A. Papamicael et al.: Synthesis of C1- and C3ꢀ-Symmetric Porphyrin Trimers
796
Avance DRX 500 instrument by F. Fehr; mass spectra were
¨
recorded by F. Nydegger and I. Muller.
C1-Symmetric Triporphyrin (16, C205H118N12Zn3)
Air was removed from a soln. of 11mg 14 (9.2ꢃmol) and
28.4 mg [5-[4-[[4-[(4-iodophenyl)ethynyl]phenyl]ethynyl]-
phenyl]-10,15,20-triphenylporphinato(2-)]zinc (15) [4]
(28.2ꢃmol) in 6.4 cm3 DMF=Et3N (5:1) by blowing Ar for
20min. Then 2.08mg Pd2(dba)3 (2.28 ꢃmol) and 5.5 mg AsPh3
(18 ꢃmol) were added, and deaeration was continued for
10min. Thereafter, the mixture was heated at 40ꢃC for 4 h.
At that time, the same amount of Pd2(dba)3 and AsPh3 was
again added and the stirring continued for 3 h. The solvent
was removed under reduced pressure and the crude product
was purified after two successive CC (CHCl3=n-hexane: gra-
dient from 1=1 to 3=1) to yield 4.8mg (18%) 16. UV=VIS
(CH2Cl2): ꢁmax (log ") ¼ 354 (5.15), 420 (6.06), 548 (4.69),
586 (4.14) nm (molꢂ1 dm3 cmꢂ1); 1H NMR (500.13 MHz,
CDCl3): ꢂ ¼ 5.65 (s, 1H, CH), 7.18 and 7.54 (2ꢄAA0XX0,
4ꢄapparent d, J ¼ 8.3 Hz, 8H, H-phenylene on central CH
in medium and big ‘‘legs’’), 7.20 and 7.65 (AA0XX0, 2ꢄ
apparent d, J ¼ 8.0 Hz, 4H, H-phenylene on central CH in
small ‘‘leg’’), 7.52–7.57 (m, 16H, H-phenylene in medium
and big ‘‘legs’’), 7.61 and 7.68 (2ꢄAA0XX0, 4ꢄapparent d,
J ¼ 8.0 Hz, 8H, H-phenylene on porphyrin in medium and big
‘‘legs’’), 7.73–7.81 (m, 27H, m- and p-H-phenyl), 7.94 (m,
6H, H-phenylene on porphyrin), 8.23 (m, 24H, o-H-phenyl
and H-phenylene on porphyrin), 8.96 (s, 12H, ꢄ-H on por-
phyrin outside), 8.97 (m, 12H, ꢄ-H on porphyrin inside) ppm;
ESþ-MS (in CHCl3= HCOOH): m=z (%) ¼ 1378.7 ([M ꢂ
3Zn þ 8H]2þ), 919.3 ([M ꢂ 3Zn þ 9H]3þ) (calc. avg. mass for
C205H118N12Zn3: 2945.41).
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Reid DCW (2001) Chem Rev 101: 2751; b) Choi MS,
Yamazaki T, Yamazaki I, Aida T (2004) Angew Chem
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[2] See for example a) Carcel CM, Laha JK, Loewe
RS, Thamyongkit P, Schweikart KH, Misra V, Bocian
DF, Lindsey JS (2004) J Org Chem 69: 6739; b)
Balasubramanian T, Lindsey JS (1999) Tetrahedron 55:
6771; c) Lee CH, Li F, Iwamoto K, Dadok J, Bothner-By
AA, Lindsey JS (1995) Tetrahedron 51: 11645
[3] Mongin O, Gossauer A (1996) Tetrahedron Lett 37:
3825
[4] Mongin O, Gossauer A (1997) Tetrahedron 53: 6835
¨
[5] Vogtle F, Berscheid R, Schnick W (1991) J Chem Soc
Chem Commun 414
[6] The synthesis described in the Experimental Section
yields tris(4-iodophenyl)methane in higher purity than
the procedure reported in Ref. [9] in which direct iodin-
ation of triphenylmethane leads in fact to tris(4-iodo-
phenyl)methanol as the major product and a mixture
containing tris(4-iodophenyl)methane
[7] Farina V, Krishnan B (1991) J Am Chem Soc 113: 9585
[8] Lavastre O, Ollivier L, Dixneuf PH (1996) Tetrahedron
52: 5495
[9] Popova NI, Skubnevskaya GI, Molin Yu N, Kotlyarevskii
IL (1969) Izv Akad Nauk SSSR, Ser Khim 11: 2424
[10] Satoshi M, Takanobu N, Yoshiaki T (2005) PCT Int
Appl: 82. WO 2005030829 CAN 142: 356334 AN
2005: 300497
Acknowledgements
This work was supported in part by the Swiss National
Science Foundation. NMR spectra were recorded on a Bruker